1. Field of the Invention
The present invention relates to a color recording liquid which can be advantageously used as a coloring ink, color developer and others in an ink jet color recording, electrographic color recording and other recording or imaging systems. Using the color recording liquid according to the present invention, it becomes possible to obtain high quality black recording without causing blurring of color, along with high quality color recording having no bleeding of color in a borderline between two adjacent color recording areas of different hues. In addition to these advantages, according to the present invention, the resulting color recording can exhibit an excellent water resistance and lightfastness, good brightness and wide range of color reproduction. The present invention also relates to a cartridge containing the color recording liquid of the present invention in its containers, and a color recording method and device using the color recording liquid of the present invention. The term "recording liquid" is used herein to generally indicate an ink composition for use in color recording and therefore it is also referred to as an ink, however, it should be noted that the recording liquid or ink can be used as a developer in an electrographic color recording process and other uses, in addition to its use as a coloring ink in an ink jet color recording process.
2. Description of the Related Art
When recording or printing of images including characters, pictures and others in color (hereinafter, referred briefly to as "color recording") is done by using color recording liquids such as inks in accordance with an ink jet recording process or an electrographic recording process, so-called "bleeding of color" is frequently caused due to undesirable mixing of different color inks at a border between two adjacent color recording areas. Since the bleeding of color can deteriorate qualities of the resulting color recording, hitherto, the following methods have been suggested to solve the bleeding problem.
1) combined use of two inks which are insoluble in each other, PA1 2) use of a coloring material-providing ink which can release a coloring material as a result of the reaction, and PA1 3) improving a penetration of the ink into the recording medium, thereby accelerating a fixation of the ink to the medium. PA1 (1) yellow ink containing an anionic dye and a nonionic surfactant; PA1 (2) magenta dye containing an anionic dye and a nonionic surfactant; PA1 (3) cyan dye containing an anionic dye and a nonionic surfactant; and PA1 (4) color ink containing a cationic dye and capable of providing a black color upon mixing with any one of the color inks (1) to (3) on the recording material, and PA1 (A) providing a non-recording area in the borderline between the black recording area and the other color recording area, thereby avoiding contact of said two colors; and PA1 (B) repeatedly recording two or more types of color inks (for example, yellow, magenta, cyan) in the borderline area to thereby record a composite black having a hue which is the closest to a black, i.e., so-called "real black". These countermeasures are considered to be noticeable, however, the countermeasure (A) is insufficient to remove a remarkable whitening (formation of the white-colored area) due to presence of the non-recording area, and the countermeasure (B) causes a new problem, i.e., deterioration in the qualities of the resulting recording, due to differences in the black hue between the borderline area (composite black) and the other areas (real black owing to the black ink). PA1 either or both of said black-colored recording liquid (a) and said colored recording liquid (b) are a recording liquid which comprises water having dispersed therein a coloring material consisting of particles of colored, ionic group-containing resin and, PA1 when said coloring material-dispersed recording liquid is used as a first recording liquid along with another recording liquid, said another recording liquid is a second recording liquid which comprises water having dispersed and/or dissolved therein a coloring material consisting of an ionic group-containing compound whose ionic group has an opposite ionic character to that of the ionic group of said ionic group-containing resin. PA1 (i) a cartridge containing recording liquids which comprises, in combination, separate containers, each of which contains the black-colored recording liquid (a) and the colored recording liquid (b), separately, of the present invention; and PA1 (ii) a means for applying each of the recording liquids supplied from said containers to said recording medium in accordance with the desired recording pattern.
More particularly, the first method directed to combined use of two inks is disclosed in Japanese Unexamined Patent Publication (Kokai) No. 56-58871. The multicolor ink spraying apparatus disclosed therein is characterized by using a plurality of inks each of which contains as a solvent of the ink at least two types of liquids which are insoluble in each other. Using this method, it becomes possible to use an aqueous ink containing water, alcohols and others as a solvent (for example, red ink) and an oil-based ink containing liquid-like hydrocarbons as a solvent (for example, black ink) in an adjacent relationship on the same recording paper. Mixing of the colors can be effectively avoided, because the aqueous ink and the oil-based ink cannot be mixed due to their incompatibility.
The second method directed to use of coloring material-providing ink is disclosed in Japanese Unexamined Patent Publication (Kokai) No. 64-58583. The ink jet recording method disclosed therein is characterized by using four colors of inks including yellow, magenta and cyan and, if necessary, black, and also blending two types of inks (acid dye and basic dye) for each color in order to produce an insolubilized dye in a borderline between the two different color areas on the recording paper. According to this method, a drying capability in the color mixing areas of the recorded images can be improved, and also a satisfactory resolution and sharpness can be given to the images.
Formation of the insolubilized dye is also well-known from other patent publications. For example, Japanese Unexamined Patent Publication (Kokai) No. 1-14108 teaches the process which comprises previously adhering an anionic compound-containing liquid onto a recording medium, followed by adhering an ink containing a basic group-containing dye, or Japanese Unexamined Patent Publication (Kokai) Nos. 5-208548, 7-1837, 8-72260 and 8-72232 each teaches use, in combination, of an ink containing a dye capable of being deposited upon variation of pH value and other factors and another ink or processing solution which can change a pH value and the like, thereby causing deposition and thus insolubilization of the dye in said ink, and bring the former ink in contact with the latter ink or processing solution, thereby depositing the insolubilized dye.
The second method is also disclosed in Japanese Unexamined Patent Publication (Kokai) No. 6-191143. The ink jet color recording method disclosed therein is directed to formation of color images on a recording material by using color inks of at least four colors, and is characterized by using the following color inks (1) to (4):
mixing the color ink (4) with at least one color ink selected from the color inks (1) to (3). Using this method, even if the recording material used is a conventional plain paper, bleeding of different color dyes can be prevented in a borderline area of the colors in the plain paper, and also high quality color images having a good and uniform color density can be produced. At the same time, according to this method, the qualities of black color characters can be notable improved, and mixing of the black color with other colors can be avoided at their color borders. Namely, black color characters and color images having high qualities can be obtained. Note, however, that in the above-mentioned method, formation of the black images relies upon a black color, i.e., so-called "composite black", obtained by mixing (repeatedly recording or applying) the color inks, as is recited in the appended claims of Japanese Kokai 6-191143.
The third method is directed to an improvement of the penetration of the ink into the recording medium, and it can effectively prevent bleeding of color as a function of the shortened time of the fixation, because the inks used herein can rapidly penetrate and be absorbed in the recording medium before diffusion and mixing of different color inks are caused at their color borders, thereby ensuring an accelerated fixation of the inks.
However, the above-described first, second and third methods suffer from many problems to be solved.
For example, since it uses an oil-based ink as one ink, the first method suffers from poor handling property and is a fire hazard. Further, because they require the specific characteristics for the dyes used in the preparation of the inks, the first and second methods have a problem that the range of suitable dyes and the like for the preparation of the inks is restricted to a very narrow range, in other words, although it is desired to select the dyes capable of simultaneously satisfying a good tone of color, high weathering resistance and high reliability, it is very difficult to select such dyes. Furthermore, because two types of the inks are generally used in these methods, if there arises the necessity of using three or more types of the dyes in the preparation of the inks, some combination of the selected dyes cannot be utilized in carrying out the methods because of the poor characteristics of some of said dyes, or alternatively, it becomes necessary to use an additional and expensive solutions and means such as specific processing solutions for the inks, tanks for receiving the processing solutions, recording nozzles for spraying the processing solutions, and driving circuits and other devices for controlling the spraying of the processing solutions.
Due to the improved penetration of the inks, the third method has a tendency of causing blurring of the dyes along a length of the fibers and the like in the recording medium, when papers having an uneven surface due to exposed cellulose fibers, namely, so-called "plain papers" are used as the recording medium. Such-blurring of the dyes can result in a problem that unsharp edges are produced in the recorded images, and this problem is particularly important when the image recording is carried out by using a black ink, because an excellent sharpness is particularly required in such black image recording. Nevertheless, the third method is considered to be the most suitable one for the practical use among the described three methods, because it can notably diminish blurring of colors in the color recording using cyan, magenta and yellow inks to an acceptably reduced level.
In order to solve the above-mentioned problem concerning formation of the unsharp edges in the recorded images due to characteristics of the used black color ink, it is contemplated, as disclosed in Japanese Unexamined Patent Publication (Kokai) No. 4-147866, to use, in combination, a specific black color ink requiring an extended fixation time, thereby ensuring retarded penetration of the ink into the papers and thus inhibition of the blurring of the inks, and specific color inks having other hues than the black which can be fixed in the papers within a shorter time than the black color ink, the fixing time being sufficiently short to avoid the blurring of the inks. Accordingly, the application of the method described in Japanese Kokai 4-147866 to the above-described third method is effective to simultaneously attain black recording with high qualities having no blurring and color recording with high qualities having no bleeding of colors.
However, in the above combination of the third method and the method described in Japanese Kokai 4-147866, there remains one problem that it is still insufficient to prevent bleeding of colors in the borderline of black and other colors. To solve this problem, the prior art methods suggest the following countermeasures:
In addition to the above-discussed problems, there is a further problem concerning the difficulty in obtaining glossy recording. Hitherto, an aqueous ink has been conventional used as the jet ink, however, such an aqueous ink is unable to confer a gloss to a surface of the resulting recording. Contrary to this, particularly in the field of color recording, there has been desired to give a good gloss to the recording surface, thereby improving a visual brightness and thus obtaining high quality recording products comparable to gravure printing products. To solve this problem, one prior art method suggests use of specifically produced glossy recording papers for exclusive use in color ink jet printers, thereby obtaining a desired level of gloss. Another method is disclosed in, for example, Japanese Unexamined Patent Publication (Kokai) Nos. 3-167271 and 3-167272, and it suggests use of resinous particles as a fixing means of the coloring materials and selection of specific solvents satisfying a certain degree of the penetration into the recording medium and a certain degree of the evaporation, thereby enabling color recording with gloss. However, since the former method has a drawback that the recording papers for exclusive use are very expensive, it is desired to enable glossy recording with use of plain papers which are easily available at low costs and therefore are conventionally used in dry process copying machines. Further, the latter method has a drawback that the desired coloring effects could not be obtained, because the coloring material, particularly dyes are still dispersed in an aqueous medium, although it should be adhered to the resinous particles as a fixing means. Furthermore, in view of obtaining a high and satisfactory coloring or color development, the coloring material used should be dispersed in the aqueous medium as uniformly as possible, however, the latter method results in drawbacks such as reduction of the chroma and deterioration of the color developing performance due to insufficient dyeing of the resinous particles.